Statistical study of conductance properties in one-dimensional quantum wires focussing on the 0.7 anomaly

TL;DR

This study statistically analyzes conductance in 1D quantum wires, focusing on the 0.7 anomaly, revealing significant variability linked to device-specific potential profiles using a large array of identical split gates.

Contribution

It introduces an automated method to estimate the 0.7 structure in large data sets and correlates its variability with the confining potential in quantum wires.

Findings

The 0.7 anomaly varies significantly across devices.

The 0.7 structure is highly sensitive to the confining potential.

Large differences in the 0.7 feature are observed despite identical fabrication.

Abstract

The properties of conductance in one-dimensional (1D) quantum wires are statistically investigated using an array of 256 lithographically-identical split gates, fabricated on a GaAs/AlGaAs heterostructure. All the split gates are measured during a single cooldown under the same conditions. Electron many-body effects give rise to an anomalous feature in the conductance of a one-dimensional quantum wire, known as the `0.7 structure' (or `0.7 anomaly'). To handle the large data set, a method of automatically estimating the conductance value of the 0.7 structure is developed. Large differences are observed in the strength and value of the 0.7 structure [from $0.63$ to $0.84\times (2e^2/h)$], despite the constant temperature and identical device design. Variations in the 1D potential profile are quantified by estimating the curvature of the barrier in the direction of electron transport, following a saddle-point model. The 0.7 structure appears to be highly sensitive to the specific confining potential within individual devices.